Pete,
Some years ago I approached CIE and asked for samples of their lesson books. They sent about six lesson books (at that time the lesson books were small, just enough to cover the subject matter for that lesson). I was not particular impressed, but that's just my opinion. You should request samples lesson books from them. NRI was a better school, but they no longer exist. CIE, however, may provide the education you seek. If you want to go the extra mile, check out:
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They offer associate and bachelor degrees at the engineering level (but their accreditation may not be recognized by traditional resident colleges--meaning some colleges or universities may not allow for the transfer of credits). They are also expensive compared to schools such as CIE, about $4000 per semester. Until circumstances forced me to withdraw, I took their Electronic Technology program and it was very well done. It was this program that finally allowed me to understand parallel and series resonant circuits, such as those used in radios, etc.
For your situation, CIE may be suitable, but do a search on "electronic schools" on Google before making a decision. Also plan on buying books to supplement their program. Also plan on buying an oscilloscope. You can find hobby grade oscilloscopes for as little as $300 and you don't want to know what professional grade scopes cost. A dual trace scope is better (two inputs). The course you are considering doesn't require a scope, but when you get into AC circuitry a hobby grade scope will help you see what in heck is going on.
Note that the non-college level distance programs are designed to make you succeed. In other words, the tests are not that hard. They do this to avoid losing you as a customer who fails the tests and cancels out. It will be up to you to make sure you've obtained the knowledge no matter how easy the tests are. The diplomas are just a piece of paper.
If you are sufficiently motivated, you can buy the books and lab equipment you need to teach yourself for less than a school will charge. Search Amazon for this.
Hope this helps,
// Jim